238 SPECIAL BRONZES i gram of the alloy is dissolved in 15-20 c.c. of nitric acid (D 1-3), the solution evaporated to dryness, the residue taken up with a few drops of nitric acid and hot water, and the separate determinations carried out as with ordinary bronzes (q.v.}. 2. Determination of the Phosphorus.—i gram of the sample, as filings, is dissolved in aqua regia, evaporated to dryness, repeatedly taken up with hydrochloric acid and evaporated to dryness, and the residue dis- solved in dilute hydrochloric acid and hot water (400-500 c.c.) and the hot solution treated with hydrogen sulphide. The precipitate is washed on a Gooch crucible with hot water saturated with hydrogen sulphide and acidified with hydrochloric acid and the filtrate evaporated to dryness with nitric acid. The residue is dissolved in a little nitric acid and the phosphoric acid precipitated with ammonium molybdate as in the determination of phos- phorus in iron. * # * The following table gives the compositions of various types of commercial lead-bronzes (Guillet, Muspratt, Ledebur) : TABLE XXV Composition of Lead-bronzes Cu Sn Pb : Zu r Ft! Sb I ... 84-70 10-05 4-00 0-46 o-u __ 0-14 •2 ... 84-00 3-00 4-56 j 8-50 • — — — 3 • • • «3'85 8-32 7-36 0-13 0-31 trace . — 41 . . - 79-70 10-00 9'50 — 0-80 — . — • 5 • • • 73-50 9-50 9-50 9-50 . — . 0-50 — 6 ... 78-01 10-36 10-45 ' • o-57 0-09 — Ni 0-26 As 0-04 Manganese -bronzes Manganese-bronzes, which should not be confused with manganese- brasses—often improperly given this name—or manganese-copper alloys, are composed essentially of copper and tin with small proportions of man- ganese (1-3%). Their analysis comprises : 1. Determination of the Tin.—As in ordinary bronzes. 2. Determination of the Lead, Copper, Iron, Manganese and Zinc.—The liquid from which the metastannic acid has been separated, together with the solution of the metals occluded in the metastannic acid, is evaporated with sulphuric acid and the separate determinations carried out as with complex brasses. 3. Determination of the Phosphorus, Arsenic and Sulphur,—See Ordinary Bronzes. 1 Type adopted by the Italian State Railways.phorus in the metastannic acid separating to be borne in mind.